This invention relates to surgical apparatus for use in clearing recurring thrombosis of hemodialysis grafts.
Modern hemodialysis technology enables patients with chronic renal failure to live independently between dialysis treatments. Patients utilize this technology as a means of filtering the toxins from their blood by passing blood out of their body through a hemodialysis machine. The hemodialysis machine removes blood toxins by exposing the blood to dialyzing fluid across a semipermeable membrane, in effect creating an artificial kidney.
In order to properly process a patient""s blood a graft is made, preferably in patient""s arm. At the site of the graft a shunt is placed to connect an artery having a high rate of blood flow with a vein. The shunt provides a convenient inlet on the artery side for blood requiring dialysis filtration processing; the outlet is located on the vein side for return of dialysis processed blood from the hemodialysis station.
The dialysis shunt, while providing a convenient arrangement for hemodialysis processing, may become inoperable after a period of time due to stenosis caused by the high rate of blood flow through the shunt and repetitive injury at the venous anastomosis. Typically, patients must have these constricting portions of the shunt widened periodically in order to continue hemodialysis processing through the shunt.
Shunt blockage is generally treated through a combination of surgical devices and/or pharmaceutical treatments; these techniques are often cost prohibitive and/or require an incision. For example, pharmaceutical treatments generally employ urokinase which, depending on the amount used, can cost upward of $350.00 per application and possibly cause bleeding complications.
Mechanical thrombolysis apparatus and methods for performing thrombolysis are known, being disclosed in U.S. Pat. No. 4,646,736 to Auth, U.S. Pat. No. 5,078,722 to Stevens and U.S. Pat. No. 5,695,507 to Auth, et al.
The apparatus disclosed in these patents seeks to penetrate thrombolytic structures by introducing, for example in the case of ""507, a rotating core wire into the thrombus, seeking to withdraw fibrin from the thrombus into the rotating core wire thereby breaking up the network of the thrombus which is preventing blood flow.
In one of its aspects this invention provides a method for clearing a surgical shunt or native body lumen of thrombolytic or other undesirable material by puncturing the shunt or native body lumen to form an aperture therein, inserting a rotatable hydrophilic wire into the interior of the shunt or body lumen through the aperture and rotating the wire within the shunt or body lumen preferably at a speed sufficient to create a standing wave in an exposed portion of the wire within the shunt or body lumen to sweep the shunt or body lumen clear of thrombolytic or other undesirable material.
In another of its aspects this invention provides apparatus for clearing shunts and native body lumens of thrombolytic or other undesirable material where the apparatus preferably includes a motor preferably including control means which is preferably operable using one hand while holding the motor. The apparatus further preferably includes an elongated wire connected to the motor for rotation thereby where the wire is rotated preferably at speed sufficient to create a standing wave in the wire to rotationally sweep through the shunt or lumen to be cleared. Optionally and desirably the apparatus further preferably includes a catheter for enveloping a length of the wire and gripping means facilitating manual rotation of the catheter by one hand independently of the wire, as the wire is rotated by the motor, preferably at speed sufficient to create the standing wave in at least a portion of the wire extending from the catheter.
In further aspects of the invention the apparatus preferably includes manually actuable means for selectably connecting the wire to the motor.
Preferably the wire is hydrophilic, is not permanently deformable at room temperature and may be either braided or a single filament; a braided wire is most preferred.
Preferably the extremity of the wire remote from the catheter either is angularly disposed with respect to the remainder of the wire or is J-shaped, curving back towards the motor.
In another of the apparatus aspects of the invention, the extremity of the catheter remote from the motor may be preferably angularly disposed with respect to the remainder of the catheter. The catheter is preferably sufficiently resistant to twisting that torque manually applied to the catheter proximate the motor results in corresponding angular rotary movement of the extremity of the catheter remote from the motor.
When the wire is in the form of a single filament, the extremity of the filament extending from the catheter is preferably at an angle to the axis of the filament.
In yet another of its aspects the invention preferably provides first means communicating with the interior of the catheter for selectably supplying or exhausting fluid to and from the catheter interior.
In yet another aspect of the invention the apparatus may preferably further include a sheath enveloping the catheter and a conduit communicating with the interior of the sheath for selectably supplying or exhausting fluid to and from the sheath interior, externally of the catheter. When such a second conduit is present, the second conduit is preferably movable longitudinally along the wire with the sheath.
The gripping means for the catheter is preferably fixedly connected to the first conduit means communicating with the catheter interior and is preferably rotatable unitarily with the catheter about the wire.
In yet another of the apparatus aspects of the invention, the second conduit, the sheath, the motor, the catheter, the first conduit and the wire are all preferably manually disassemblable from one another preferably without use of tools.
In yet another apparatus aspect of the invention, the apparatus preferably further includes a housing for the motor and the control means, where the housing is adapted for grasping by one hand for operator control of the apparatus and where the wire passes through the housing and emerges from an opposite side thereof.
The motor may be electrically, pneumatically or hydraulically powered; electrical power is preferable.
In yet another of its aspects, the method of the invention further includes moving the rotating wire, with a vibrational node extant therein, axially along the lumen to rotationally sweep thrombolytic or other undesirable material from the shunt or lumen in a circumferentially sweeping action.
In a method aspect of the invention, when the rotatable hydrophilic wire is inserted into the interior of the shunt or lumen there is desirably provided a catheter surrounding the hydrophilic wire from which the wire extends into the interior of the shunt or lumen through the aperture.
In a method aspect of the invention, a rotating step desirably further includes rotating the wire but not the catheter within the shunt or lumen at a speed at which the wire forms at least one vibrational node in the portion of the wire extending from the catheter tip within the shunt or lumen.
Most desirably the method aspect of the invention further includes rotating the wire but not the catheter within the shunt or lumen at a speed from about 100 revolutions per minute to about 10,000 revolutions per minute.
In the method aspect of the invention, wire rotation may be performed manually or by a motor rotating the wire within the shunt or lumen. In either event the wire is preferably rotated at a speed at which the wire forms at least one vibrational node in the portion of the wire within the lumen, most preferably in the portion of the wire extending outwardly of the catheter. The wire is desirably moved along the shunt or lumen longitudinally by moving the motor; orientation of the wire within the shunt or lumen is desirably controlled by rotating the catheter, preferably manually.
The motor is most preferably a hand-held motor; moving the wire along the shunt or lumen is most preferably performed by manually moving the motor. Controlling orientation of the wire is preferably performed by manually rotating the catheter. All of these manual operations are preferably performed using only one hand.
In a method aspect of the invention, the rotating step is preferably performed by rotating the wire within the shunt or lumen along the length of the shunt or lumen for a time sufficient to macerate thrombolytic material within the shunt or lumen and thereby produce a standing column of liquified material therewithin.
In another of its aspects, the invention provides a method for clearing a surgical shunt connecting an artery to a vein and associated portions of said artery and vein of thrombolytic material by initially inserting a needle through a patent""s skin and into the shunt, inserting a first wire through the needle, sensing whether the first wire is in the shunt preferably by tactile sensation received via the wire, x-ray inspecting skin preferably where the needle was inserted to determine whether the wire is within the shunt, removing the needle when the wire is determined to be within the shunt, placing a first catheter over the first wire with a catheter discharge orifice within the shunt, removing the first wire leaving the first catheter with the discharge end within the shunt, inserting a second wire through the first catheter into the interior of the shunt, removing the first catheter from the shunt, inserting a sheath over the second wire and into the shunt, removing the second wire, inserting a rotatable instrument wire and an associated surrounding catheter through the sheath and into the shunt, supplying lubricating fluid to the associated catheter interior to lubricate the instrument wire for rotation within the associated catheter, sweepingly rotating the instrument wire, but not the associated catheter, through the shunt to liquify thrombolytic material therein, removing the instrument wire and associated catheter from the sheath, applying suction to the sheath to remove liquid thrombolytic material from the shunt interior, injecting anti-coagulant into the shunt interior through the sheath, removing the instrument wire from the associated catheter, disconnecting the instrument wire from a drive motor associated therewith, re-inserting the instrument wire without the associated catheter through the sheath into the shunt interior and through any blockage at the vein end of the shunt and into the vein, placing an angioplasty balloon over the instrument wire, pushing the angioplasty balloon into position within venous anastomosis at vein-shunt juncture, removing the wire leaving the angioplasty balloon in position within the venous anastomosis at vein-shunt juncture, injecting radiology contrast dye through a lumen of the balloon vacated by removal of the instrument wire therefrom, observing dye travel through the vein to the patient""s heart to reveal any venous blockages, inserting the instrument wire back into the balloon lumen, inflating the balloon to crush any venous anastomosis and open shunt-vein juncture, removing the balloon and instrument wire from the sheath, inserting a second sheath between the position of first sheath insertion and shunt-vein juncture into a shunt interior region cleansed of thrombolytic material, re-inserting the instrument wire without the associated catheter through the second sheath into the shunt through any blockage at shunt-artery juncture, placing an angioplasty balloon over the wire, pushing the balloon into position within arterial anastomosis at artery-shunt juncture, removing the wire leaving the angioplasty balloon in position, injecting contrasting radiology dye through the balloon lumen vacated by the wire, observing travel of the dye through the artery to the heart thereby revealing any arterial blockages, inserting the instrument wire back into the balloon lumen, inflating the balloon to crush any arterial anastomosis and thereby open shunt-artery juncture, removing a platelet plug and residual arterial anastomosis from the shunt-artery juncture by pulling on the balloon and, finally, removing the balloon, wire and sheath from the patient.
The apparatus may include a hydrophilic wire which is placed into the shunt access port, advanced to the blockage within a lubricated catheter which is steerable and is rotated, with the same hydrophilic wire extending beyond the tip of the directional catheter about its longitudinal axis thereby separating material adhering to the inside surface of the dialysis shunt and mechanically macerating the thrombus.
During rotation, the exposed length of the hydrophilic wire preferably begins to periodically flex in an oscillatory fashion, forming a standing wave contributing to the ability to clear the length of the shunt. The maximum deflection points of the rotating wire allow shunt cleansing by rotating the oscillatory wire providing a scouring action clearing the wall of adherent thrombus while also breaking up clots within the graft. The tip of the hydrophilic wire is preferably translated into and out of the thrombus within the shunt thereby mechanically disrupting and dissolving clots in both directions of translation and hence decreasing time necessary to complete thrombolysis. The wire can then be disassembled from the device and used as necessary to complete a shunt renewal procedure.
In another of its aspects the invention provides a method for clearing dialysis shunts. A catheter entrance port is prepared for reception of the hydrophilic wire apparatus. The tip of the wire is advanced into the clot; the wire is rotated preferably by an electric motor such that the hydrophilic wire rotates about its longitudinal axis within a lubricated catheter, with rotation of the wire creating an oscillatory flexing of the hydrophilic wire along substantially its length outside of the lubricating directional catheter.